Ultimately, that's for buyers to decide. The problem is that every millimetre shaved off the thickness of a portable PC involves compromising on features, and pushes up the price. The last company to produce an ultra-thin notebook - Sony launched the Vaio X505 in 2004 - soon withdrew it, because it involved too many compromises. Apple's new MacBook Air unveiled this week, has even more.

The trend towards laptop slimness is a result of progress in LCD screens, which have been getting bigger and cheaper for the past two decades. The downside is that as screens get bigger, so do notebook computers. With the length and width fixed by the screen, there's only one thing manufacturers can cut: the depth.

But making computers ultra-thin creates a number of challenges, the first of which is flex. Twist the corners under pressure (eg when toting the laptop around in a bag) and the case flexes but the LCD screen doesn't. Result: a cracked screen.

Then there's heat. Chips get hot, so it's good to have air around them, and fans to dissipate the heat. Ultra-thin cases just make that problem worse. As Apple has elected not to pay the price of putting a proper ultra-low voltage (ULV) chip in the MacBook Air, as Sony did, we're waiting to see just how hot it gets.

To make the Air so thin, Apple has simply been prepared to make more compromises than anybody else. It has left out the optical CD/DVD drive and the expansion card slot. There's no Ethernet port for plugging into the net (it relies on Wi-Fi), no FireWire port, no Kensington anti-theft lock, and only one solitary USB port. Worst of all, users can't even change the battery, which kills the machine for real "road warriors" who like to carry one or two spares.

It's a lot to give up when you're only saving 6mm (less than ¼ inch) at its thickest over a MacBook Pro or 5mm over a Sony Vaio G11.

The Air looks great, of course, but Apple may just find it has taken thinness a few millimetres too far.Jack Schofield

What does the British Council do?

It has taken the heavy hand of Russia's federal security service (FSB) to lift the British Council out of obscurity. For most of its 74 years, the council has been better known abroad than in Britain, where it has been satirically portrayed as a home-from-home for librarians in beards and/or sandals.

The FSB, the renamed but largely unreformed KGB, has made it a martyr for the cause of Shakespeare, Britart and the English language, propelling the council deep into Le Carré territory. The head of its St Petersburg office has been followed through the dark, icy streets of the city and held on dubious traffic charges. Its Russian staff have been asked ominous questions about the welfare of relatives and pets by FSB goons.

According to a spokeswoman, this is the first time the council has been in this kind of trouble. It promotes British culture, language and education in 110 countries, including all manner of troublespots, from Baghdad to Kabul. In Peshawar, it is offering English-language training to teachers in religious schools, madrasas, with the aim of moderating the influence of jihadist Islam along the Afghan-Pakistan border.

The council was set up by an ambitious Australian at the Foreign Office, who persuaded his employers to fund lecture tours and book donations in the name of "cultural propaganda" in 1931. The effort was formalised into an autonomous organisation in 1934. It now describes its mission as to "connect people with learning opportunities and creative ideas from the UK to build lasting relationships around the world".

Under the chairmanship of Lord Kinnock (whose son, Stephen, was pursued by the FSB through St Petersburg) much of the council's work now focuses on teaching English. That goal was made all the more central by Gordon Brown's announcement this week that he wanted to boost English as "the world's language", with the help of a new website run by the British Council. Its time has undoubtedly come, with no small thanks to Vladimir Putin. Julian Borger

Will Kevin Keegan save Newcastle?

Kevin Keegan's reappearance on Tyneside as Newcastle United's manager represents an impressive third coming for the man once described as the Geordie messiah. Floundering after the sacking of Sam Allardyce - their 10th manager in 11 years - the club have pulled off something of a coup in luring out of retirement the former Newcastle player, later the most celebrated manager in their recent history.

But will it work? Allardyce was sacked largely because of the way his team played the game, prizing pragmatism over style and generally failing to provide the desired thrills and spills. Keegan, with his irrepressible cheeriness, his man-of-the-people demagoguery and, above all, his commitment to playing attacking football, has already transformed the mood of the place.

Newcastle occupy a middle- ranking position in the self-sustaining oligopoly of established Premier League clubs. Too wealthy to struggle unduly, not wealthy enough to buy genuine success, clubs of this size tend simply to hover in a gently shuffling pack behind Chelsea, Arsenal, Liverpool and Manchester United. Finishing fifth would represent success for Keegan. Or, if this seems too ambitious, he could probably get away with making fans feel as though they've been entertained.

Whether it's ever a very good idea to go back is another question. After two years managing a children's project near Glasgow, this is his most unexpected entrance, one possibly clouded by an irresistible desire for one last incarnation on Tyneside as a footballing cure for bad morale and iffy results. Most ersatz messiahs end up being something of a disappointment. This one, at least, should be lots of fun to watch while he's among us.Barney Ronay